A conventional color camera using CCD devices is described in the Japanese Patent Kokai No. 60-263458. In this conventional color camera, each of the CCD devices comprises a photodiode, a CCD channel, a light shielding layer for supplying an input light not to the CCD channel, but to the photodiode, and a micro lens for focusing the input light on the photodiode. Such CCD devices are provided for red, green and blue color lights on a semiconductor substrate.
In operation, each color input light is supplied to a corresponding photodiode, in which electric charges are accumulated. Then, the accumulated electric charges are transferred to the CCD channel by applying a pulse to an electrode which is provided on the CCD channel. Thus, an output signal is obtained for each of the red, green and blue input color lights.
In the conventional color camera, however, there is a disadvantage in that a high sensitivity is difficult to be obtained in all of the three primary colors, because signal output levels for the red and blue color lights are lower than that for the green color light under the condition of a large aperture of a lens diaphragm, for instance, when a curvature of the micro lens and a thickness of a resin film provided between the micro lens and the photodiode are optimized for the green color light having a wavelength shorter than that of the blue color light and longer than that of the red color light. The detailed explanation on this disadvantage will be made immediately prior to the description of the preferred embodiments.